if you want to polish the sear mating surfaces, use arm and hammer baking soda toothpaste.
I'm truly surprised to hear that Hungry/tactical teacher is advising the use of lapping compound......
a trigger job addresses a whole lot more than the polishing of sear and hammer hook mating surfaces, which in Chinese trigger groups, are rarely symmetrical in how they make contact.
a trigger job done correctly will eliminate hammer wall/sear contact first, true the spring to correct length next, then sear mating surfaces are trued and polished and hammer hooks trued and polished. once all that is done, pull weight is established and either increased or decreased as necessary.
no lapping compound I've ever read about or used will do all that for you...... a standard trigger job that is. that's without even touching on any "NM modifications"